PHP缩略图函数

考虑到页面加载速度和页面布局的需要,很多时候要将用户上传的图片进行缩略,下面这个函数分享出来,希望对大家有用。
它支持gif、jpg、png和bmp几种图片格式,不过bmp图像需要ImageCreateFromBMP函数支持。

/**
 * $srcFile - 图形文件
 * $pixel - 尺寸大小,如:400*300
 * $_quality - 图片质量,默认75
 * $cut - 是否裁剪,默认1,当$cut=0的时候,将不进行裁剪
 * $cache - 如果有缓存,是否直接用缓存,默认true
 * 示例:"< img src=\"".MiniImg('images/image.jpg','300*180',72,0)."\">"
 * */
function MiniImg($srcFile, $pixel, $_quality = 75, $cut=1, $cache=true){
	$_type = strtolower(substr(strrchr($srcFile,"."),1));
	$pixelInfo = explode('*', $pixel);
	$pathInfo = pathinfo($srcFile);
	$_cut = intval($cut);
	$searchFileName = preg_replace("/\.([A-Za-z0-9]+)$/isU", "_".$pixelInfo[0]."x".$pixelInfo[1]."_".$cut.".\\1", $pathInfo['basename']);
	$miniFile = $pathInfo['dirname'].'/'.$searchFileName;
	if($cache and file_exists($miniFile)) return $miniFile;
	$data = GetImageSize($srcFile);
	$FuncExists = 1;
	switch ($data[2]) {
		case 1:			//gif
			if(function_exists('ImageCreateFromGIF')) $_im = ImageCreateFromGIF($srcFile);
			break;
		case 2:			//jpg
			if(function_exists('imagecreatefromjpeg')) $_im = imagecreatefromjpeg($srcFile);
			break;
		case 3:			//png
			if(function_exists('ImageCreateFromPNG')) $_im = ImageCreateFromPNG($srcFile);  
			break;
		case 6:			//bmp,这里需要用到ImageCreateFromBMP
			$_im = ImageCreateFromBMP($srcFile);  
			break;
	}
	if(!$_im) return $srcFile;
	$sizeInfo['width'] = @imagesx($_im);
	$sizeInfo['height'] = @imagesy($_im);
	if(!$sizeInfo['width'] or !$sizeInfo['height']) return $srcFile;
	if($sizeInfo['width'] == $pixelInfo[0] && $sizeInfo['height'] == $pixelInfo[1] ) {
		return $srcFile;
	}elseif($sizeInfo['width'] < $pixelInfo[0] && $sizeInfo['height'] < $pixelInfo[1] && $miniMode=='2'){
		return $srcFile;
	}else{
		$resize_ratio = ($pixelInfo[0])/($pixelInfo[1]);
		$ratio = ($sizeInfo['width'])/($sizeInfo['height']);
		if($cut==1){
			$newimg = imagecreatetruecolor($pixelInfo[0],$pixelInfo[1]);
			if($ratio>=$resize_ratio){										//高度优先
				imagecopyresampled($newimg, $_im, 0, 0, 0, 0, $pixelInfo[0],$pixelInfo[1], (($sizeInfo['height'])*$resize_ratio), $sizeInfo['height']);
				$_result = ImageJpeg ($newimg,$miniFile, $_quality);
			}else{															//宽度优先
				imagecopyresampled($newimg, $_im, 0, 0, 0, 0, $pixelInfo[0], $pixelInfo[1], $sizeInfo['width'], (($sizeInfo['width'])/$resize_ratio));
				$_result = ImageJpeg ($newimg,$miniFile, $_quality);
			}
		}else{																//不裁图
			if($ratio>=$resize_ratio){
				$newimg = imagecreatetruecolor($pixelInfo[0],($pixelInfo[0])/$ratio);
				imagecopyresampled($newimg, $_im, 0, 0, 0, 0, $pixelInfo[0], ($pixelInfo[0])/$ratio, $sizeInfo['width'], $sizeInfo['height']);
				$_result = ImageJpeg ($newimg,$miniFile, $_quality);
			}else{
				$newimg = imagecreatetruecolor(($pixelInfo[1])*$ratio,$pixelInfo[1]);
				imagecopyresampled($newimg, $_im, 0, 0, 0, 0, ($pixelInfo[1])*$ratio, $pixelInfo[1], $sizeInfo['width'], $sizeInfo['height']);
				$_result = ImageJpeg ($newimg,$miniFile, $_quality);
			}
		}
		ImageDestroy($_im);
		ImageDestroy($newimg);
		if($_result) return $miniFile;
		return $srcFile;
	}
}

以下是ImageCreateFromBMP函数
ImageCreateFromBMP() – 支持BMP图片函数

/**
 * ImageCreateFromBMP() - 支持BMP图片函数
 * $filename - BMP图形文件
 * */
function ImageCreateFromBMP( $filename ) { 
	// Ouverture du fichier en mode binaire 
	if ( ! $f1 = @fopen ($filename, "rb")) return FALSE ; 
	// 1 : Chargement des ent?tes FICHIER 
	$FILE = unpack ( "vfile_type/Vfile_size/Vreserved/Vbitmap_offset" , fread($f1 ,14)); 
	if ( $FILE ['file_type'] != 19778 ) return FALSE ; 
	// 2 : Chargement des ent?tes BMP 
	$BMP = unpack ( 'Vheader_size/Vwidth/Vheight/vplanes/vbits_per_pixel' . 
			'/Vcompression/Vsize_bitmap/Vhoriz_resolution' . 
			'/Vvert_resolution/Vcolors_used/Vcolors_important' , fread ( $f1 , 40 )); 
	$BMP [ 'colors' ] = pow ( 2 , $BMP['bits_per_pixel ' ]); 
	if ( $BMP ['size_bitmap'] == 0 ) $BMP ['size_bitmap']=$FILE ['file_size']-$FILE ['bitmap_offset']; 
	$BMP ['bytes_per_pixel'] = $BMP ['bits_per_pixel'] / 8 ; 
	$BMP ['bytes_per_pixel2'] = ceil ( $BMP ['bytes_per_pixel']); 
	$BMP ['decal'] = ( $BMP ['width']*$BMP ['bytes_per_pixel'] / 4 ); 
	$BMP ['decal'] -= floor ( $BMP ['width'] * $BMP ['bytes_per_pixel'] / 4 ); 
	$BMP ['decal'] = 4 - ( 4 * $BMP ['decal']); 
	if ( $BMP ['decal'] == 4 ) $BMP ['decal'] = 0 ; 
	// 3 : Chargement des couleurs de la palette 
	$PALETTE = array (); 
	if ( $BMP ['colors'] < 16777216 ){ 
		$PALETTE = unpack ( 'V' . $BMP ['colors'] , fread ( $f1 , $BMP ['colors'] * 4 )); 
	} 
	// 4 : Cr?ation de l'image 
	$IMG = fread ( $f1 , $BMP ['size_bitmap']); 
	$VIDE = chr ( 0 ); 
	$res = imagecreatetruecolor( $BMP ['width'] , $BMP ['height']); 
	$P = 0 ; 
	$Y = $BMP ['height'] - 1 ; 
	while ( $Y >= 0 ){ 
		$X = 0 ; 
		while ( $X < $BMP ['width']){ 
			if ( $BMP ['bits_per_pixel'] == 24 ) 
				$COLOR = @unpack ( "V" , substr($IMG,$P,3).$VIDE ); 
			elseif ( $BMP['bits_per_pixel']== 16 ){ 
				$COLOR = unpack ( "n" , substr ( $IMG , $P , 2 )); 
				$COLOR [1] = $PALETTE [ $COLOR [ 1 ] + 1 ]; 
			}elseif ( $BMP['bits_per_pixel']== 8 ){ 
				$COLOR = unpack ( "n" , $VIDE . substr ( $IMG , $P , 1 )); 
				$COLOR [1] = $PALETTE [ $COLOR [ 1 ] + 1 ]; 
			}elseif ( $BMP['bits_per_pixel']== 4 ){ 
				$COLOR = unpack ( "n" , $VIDE . substr ( $IMG , floor ( $P ) , 1 )); 
				if (( $P * 2 ) % 2 == 0 ) 
					$COLOR [1] = ( $COLOR [1] >> 4 ) ; 
				else 
					$COLOR [1] = ( $COLOR [1] & 0x0F ); 
				$COLOR [1] = $PALETTE [ $COLOR [1] + 1 ]; 
			}elseif ( $BMP['bits_per_pixel']== 1 ){ 
				$COLOR = unpack ( "n" , $VIDE . substr ( $IMG , floor ( $P ) , 1 )); 
				if (( $P * 8 ) % 8 == 0 ) $COLOR [ 1 ] = $COLOR [ 1 ] >> 7 ; 
				elseif (( $P * 8 ) % 8 == 1 ) $COLOR [1] = ( $COLOR [1] & 0x40 ) >> 6 ; 
				elseif (( $P * 8 ) % 8 == 2 ) $COLOR [1] = ( $COLOR [1] & 0x20 ) >> 5 ; 
				elseif (( $P * 8 ) % 8 == 3 ) $COLOR [1] = ( $COLOR [1] & 0x10 ) >> 4 ; 
				elseif (( $P * 8 ) % 8 == 4 ) $COLOR [1] = ( $COLOR [1] & 0x8 ) >> 3 ; 
				elseif (( $P * 8 ) % 8 == 5 ) $COLOR [1] = ( $COLOR [1] & 0x4 ) >> 2 ; 
				elseif (( $P * 8 ) % 8 == 6 ) $COLOR [1] = ( $COLOR [1] & 0x2 ) >> 1 ; 
				elseif (( $P * 8 ) % 8 == 7 ) $COLOR [1] = ( $COLOR [1] & 0x1 ); 
				$COLOR [1] = $PALETTE [ $COLOR [1] + 1 ]; 
			}else return FALSE ; 
			imagesetpixel( $res , $X , $Y , $COLOR [ 1 ]); 
			$X ++ ; 
			$P += $BMP['bytes_per_pixel']; 
		} 
		$Y -- ; 
		$P += $BMP['decal']; 
	} 
	// Fermeture du fichier 
	fclose ( $f1 ); 
	return $res ; 
} 

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